Mysterious Poliovirus Outbreak in 2014 Likely Caused by Lab Escape: New Analysis

Transmission electron microscopy micrograph of poliovirus virions.Photo byPublic Domain.

In 2014, a 4-year-old child in China mysteriously contracted polio, a disease that is now extremely rare thanks to widespread vaccination efforts. But according to a recent study published in Virus Evolution, the virus that infected this child might not have originated naturally, but may have come from a laboratory or a vaccine production facility.

A Rediscovered Time Capsule

The origins of this mystery can be traced back to an unexpected find at the Pasteur Institute in Paris. While complying with global efforts to destroy old poliovirus samples, researchers discovered four vials labeled by Albert Sabin, a pioneering figure in polio research. These samples, sent to the institute over 60 years ago, were sequenced before being destroyed.

One of the samples, named "Glenn," bore a striking genetic resemblance to a virus isolated from the child in China in 2014. This sparked a theory that the child’s virus, known as WIV14, might have come from a laboratory environment or a vaccine manufacturing facility.

What’s even more surprising is how closely this virus resembles the Saukett poliovirus strain, still used in making inactivated polio vaccines.

Lab Leak or Vaccine Mishap?

WIV14 was initially sequenced at the Wuhan Institute of Virology (WIV), a fact that has fueled speculation, particularly in the politically charged environment where debates about lab leaks vs. natural origin of COVID-19 are frequent.

But there is no evidence that the virus came from the WIV itself. Instead, researchers suspect the virus could have leaked from a facility that handled Saukett strains, possibly during vaccine production.

The exact route by which the virus infected the child remains a mystery. There are several potential scenarios: the virus might have accidentally contaminated samples, or it could have lingered in a freezer for years before somehow being released.

While some virologists lean toward the idea of a production facility leak, others suggest that the virus could have originated in a research lab or even a teaching institution.

The Risks of Poliovirus in Labs

Polio, once a major public health concern, has been nearly eradicated, with only a few countries still reporting cases.

But the use of live viruses in vaccines, particularly the attenuated strains in oral vaccines, poses risks. These live viruses can mutate and continue circulating, as was suspected with WIV14. Even more concerning is the potential for accidents in labs or vaccine production plants.

In the past, there have been several known cases of poliovirus leaks from laboratories. In Belgium in 2014, a vaccine production facility released billions of poliovirus particles into the sewage system, though no human cases were recorded. Other incidents include a lab worker in the Netherlands becoming infected after an accidental exposure in 2017 and again in 2022.

The possibility of poliovirus escaping from labs is a constant concern for virologists. According to Adam Lauring, an evolutionary virologist at the University of Michigan, who edited the recent paper, vaccine production plants that grow large quantities of the virus are especially risky.

Despite stringent biosafety measures, leaks can still occur, and the virus can survive for extended periods outside a lab environment.

The Importance of Investigation

While researchers stop short of pointing fingers, the need to investigate the origins of this virus is critical. “It’s terribly important to get to the bottom of any leak,” Roland Sutter, former head of polio research at the Global Polio Eradication Initiative, said. But such investigations, especially in sensitive environments, may not always be transparent.

Lauring emphasizes that safety remains a top priority in labs that handle viruses like poliovirus. He admits to taking extreme precautions when handling the virus during his own research, even going so far as to remove his clothes before entering his home to protect his family. This underscores how seriously virologists take the potential risks.

Conclusion

The case of the poliovirus infection in China is a stark reminder that even as we edge closer to eradicating deadly diseases like polio, the risk of accidental releases from labs or vaccine production facilities remains real.

As efforts continue to destroy old virus samples and sequence their genomes for future reference, it is crucial to remain vigilant about possible accidents. Ultimately, whether WIV14 originated from a lab or a production facility, the focus must remain on preventing future leaks and protecting global health.